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alkaline phosphatase
Alkaline phosphatase (ALP, ALKP, ALPase, Alk Phos) () is a hydrolase enzyme responsible for removing phosphate groups from many types of molecules, including nucleotides, proteins, and alkaloids. The process of removing the phosphate group is called ''dephosphorylation''. As the name suggests, alkaline phosphatases are most effective in an alkaline environment.
It is sometimes used synonymously as basic phosphatase.
==Bacterial==
In Gram-negative bacteria, alkaline phosphatase is located in the periplasmic space, external to the cell membrane. Since this space is much more subject to environmental variation than the actual interior of the cell, bacterial alkaline phosphatase is comparatively resistant to inactivation, denaturation, and degradation, and also has a higher rate of activity. Although the purpose of the enzyme is not fully resolved, the simple hypothesis that it is a means for the bacteria to generate free phosphate groups for uptake and use is supported by the fact that alkaline phosphatase is usually produced by the bacteria only during phosphate starvation and not when phosphate is plentiful. However, other possibilities exist. For instance, the presence of phosphate groups usually prevents organic molecules from passing through the membrane; therefore, dephosphorylating them may be important for bacterial uptake of organic compounds in the wild. Some complexities of bacterial regulation and metabolism suggest that other, more subtle, purposes for the enzyme may also play a role for the cell. In the laboratory, however, mutant ''Escherichia coli'' lacking alkaline phosphatase survive quite well, as do mutants unable to shut off alkaline phosphatase production.
The optimal pH for the activity of the ''E. coli'' enzyme is 8.0 while the bovine enzyme optimum pH is slightly higher at 8.5.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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